It is the goal of this research to elucidate the molecular events leading to the formation of an infectious enveloped virus (the alphavirus Sindbis) from its component parts. Specifically, this research program will have four primary goals: 1) The elucidation of the types of virus protein/protein interactions and processing events essential for transport and assembly of virus components into infectious virions; 2) The identification of host functions involved in the transport and development of functional virus membrane proteins; 3) Determination of the 3-dimensional structure of Sindbis virus by X-ray crystallography; 4) The elucidation of the organization of Sindbis virus RNA and protein interactions within the nucleocapsid. In pursuing these objectives, information will be gathered which is important to understanding the mechanisms employed by cells in the production, processing and transport of cell plasma membrane proteins, as well as the molecular organization of the RNA, lipid, and protein components of an important group of human and animal pathogens.